With the efficacious blast off of the
Mars Orbiter (Mangalyaan) from the Satish Dhawan Space Centre, Sriharikota at
14:38pm yesterday, India has successfully launched its inter-planetary mission
campaign. This Mars Orbiter Mission (MOM) is incidentally the 25th
launch for the PSLV which has been the most promising satellite launcher for
India so far. ISRO has been pounded by the congratulatory messages on the
successful launch of the Mars Orbiter into the earth’s orbit. The successful
deployment of the solar panels by the satellite has further vitalised India’s
robust and meticulous deep-space mission a winning start.
There are three crucial phases in this illustrious odyssey to
the red planet. The first phase of geo
centric phase has thus been successful as the fourth and the crucial phase of
the ignition was accomplished with remarkable accuracy. The journey so far has
been on expected lines and the data from the navigation ships stationed 3000
nautical miles from Fiji in the South Pacific Ocean has further confirmed the
satellite’s transition into the earth’s orbit. The satellite will make
circumambulations of earth for three weeks after it is put in the elliptical
orbit of 250 (perigee) kilometres by 23,500 (apogee) kilometers. Unlike the
Chandrayaan-1 which had to travel four lakh kilometres, the Mars Orbiter has to
travel around 200 million to 400 million km, hence ISRO will fire the 440
Newton engine on board at the orbiter’s perigee and keep incrementally increasing
its apogee. A prolonged firing will
catapult the space craft out of the earth’s orbit and it will enter the
heliocentric orbit. On Dec 1st around 12:42 pm, satellite will start
its 9 month long journey to Mars. It is expected to reach the Martian Orbit by
Sep 24th 2014. As the Orbiter approaches Mars, the Newton 440 engine
is slowed down to enable the spacecraft to enter the Martian Orbit. The most
crucial challenge in this entire mission is that the gap between the first
firing and the subsequent one would be 300 days.
As the spacecraft makes several earth bound orbits, before
entering the Martian Orbit, it has to pass through high-radiation environment
of high energy electrons in the Van Allen Belts surrounding earth. Accordingly, the spacecraft’s components have
been designed to withstand the cumulative effects of the radiations. Hence,
radiation shielding or radiation hardening has been provided with Aluminium
coating to the components.
The engine will be subsequently fired and oriented after remaining
idle for 300 days to enter the elliptical orbit of Mars 377km by 80,000km. The
spacecraft is reoriented by delaying the fourth stage of ignition to use minimum
energy to enter the Martian Orbit. This is otherwise referred to as increasing
the coasting phase between the third stage (PS3) and the fourth stage (PS4)
ignition. The coasting phase has been increased to 20 minutes to achieve the
correct argument of perigee at the time of injection into the earth’s orbit from
the PS4. This long coasting phase has been detected by the two ship borne
terminals. The text-book perfect execution of events during the ignition phase
on the launch day has further strengthened the confidence of the investigators
about the success of later events of the mission.
The 450 crore satellite has a life span of six months and
will carry out various scientific experiments with the five instruments on
board. All the instruments have been
indigenously built. The Space Application Centre, Ahmedabad has made the
methane and infrared sensor. Great deal of importance was assigned to detect
the presence of methane gas, which is an indicator of life. Hence, a methane
sensor is part of the pay loads. The thermal infrared sensor will give
information about the origin of methane whether it comes from a biological or
geological process. The Lyman Alpha Photometer made by the Laboratory for
Electro-Optic Systems (LOES), Bangalore will measure the relative amounts of
Deuterium to Hydrogen which will help in understanding the loss of water. The
presence of water on Mars was detected by the Curiosity rover of NASA. Another
instrument Martian Exospheric Neutron Composition Analyser or MENCA made by the
Space Physics Laboratory, Thiruvananthapuram will look at the exosphere of
Mars. The Mars colour Camera will help in the optical imaging of Mars surface.
The cost of the mission has been minimal as all the instruments and the
equipment have been indigenously built. The Chandrayaan -1 had several
instruments on board and it was a kind of International Mission with India as
the Captain. But Mars Mission doesn’t have any foreign payload as there was a
short gap of time between the time of announcement of the project and its
execution. Hence the ISRO had to keep it as a close family affair instead of looking
for partners. The project was accomplished in the record time of 18 months.
The Mars Mission would have two unique opportunities for
major study during its eventful stay of 6 months. One of the Mars satellite
Phobos will be in close vicinity to Mars Orbit and hence our Orbiter can study
it. According to NASA’s forecast a comet is going to pass by the side of Mars
at a distance of 50,000 kilometers. This will be another opportunity to observe
the comet.
The entire Mars Mission is very complex and it is full of
several technical challenges and one of it is communication with the satellite.
The huge distance between the earth and Mars results in greater delay in
communication. It takes atleast 20 minutes for a signal to reach Mars and
another 20 min to receive the telemetry from the satellite. Hence to counter
the difficult ISRO has built the spacecraft with autonomy. If any anamoly or
misbehaviour were to occur, the Orbiter is equipped with sensors and
transmitters on board that can detect any failure and reconfigure the system to
enter into a redundant mode. The reconfiguration occurs autonomously in the Orbiter.
Apart from the communication, power requirements also pose a tougher challenge
as the orbit of Mars is farther from sun. Thus, it receives 42% less solar
energy than earth. To compensate for the lower solar irradiation, three solar
panels capable of generating 840 watts are accommodated on the Orbiter. A
single lithium ion battery supplies power during the eclipse phases in the
geocentric phase and Martian Orbit.
Three other missions European Space Agency (ESA) of European
Consortium, National Aeronautics Space Administration (NASA) of the US and
Roscosmos of Russia have been successful in their missions to the red planet.
This maiden inter-planetary mission initiated by ISRO
scientists has been a modest attempt to explore the space with the available
resources at its behest. Undoubtedly, they have proved their mettle and gave
wings to dreams of millions of young Indians. This impeccable launch must have
boosted the morale of the Indian scientists with the Mars Orbiter have several
thousands of miles to go......
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